Process for improving cotton



Patented Nov. 19, 1%29 PATENT OFFICE LEON LILIENFELD', F VIENNA, AUSTRIA PROCESS FOR IMPROVING COTTON No Drawing. Application filed May 10, 1924, Serial No. 712,473, and in Austria May 23, 1923.

The hitherto known processes one of which, for example, is described in United States patent to Aykroyd No. 657,849, of imparting a silk-like lustre or a parchment-like appear- 5 ance or a durable dressing to cotton fabric or yarn consist in impregnating the cotton fabric or yarn with caustic alkali solution, removing the excess of caustic alkali solutlon by pressing or centrifuging or the like and then subjecting the so treated cotton fabric or yarn to the action of carbon bisulphide mostly in vapor form.

Consequently, in the processes known heretofore, the xanthate reaction takes place in the absence of an excess of caustic alkali solution, and the full amount of the soluble cellulose xanthate produced from the cotton fibre is precipitated on an/or' in the cotton fibre in the form of cellulose regenerated from said 29 xanthate. In other words: The known processes of improving cotton by treating it with caustic alkali solution and carbon bisulphide lean upon methods adopted in the viscose art.

The present invention is based upon the discovery that very valuable properties are imparted to cotton fabric or yarn.

(1) If the cotton is not converted into alkali cellulose before being treated with carbon bisulphide in presence of caustic alkali solution, viz if the carbon bisulphide is applied to the cotton before or at least as soon as the caustic alkali solution, and

(2) If the xanthate reaction takes place in presence of a considerable excess of caustic alkali solution.

The consequences of this mode of procedure, which deviates from the methods adopted in the viscose art, are:

(1) The initial swelling of the cellulose takes place in presence of carbon bisulphide, the result being that the distention of the cotton fibres and their plasticity are much greater than in the processes known hitherto, where the initial swelling takes place in absence of carbon bisulphide. Since the distention and the plasticity of the cotton fibres are the very momenta of the transformation of the dull cotton fibres into lustrous ones, the silk-like lustre obtainable in the present rocess is, among others, for this reason very igh.

(2) Owing to the fact that the reactivity towards carbon bisulphide of cellulose that has not been freed from the excess of caustic alkali solution by pressing or the like is lower than the reactivity of cellulose from Which the excess of caustic alkali solution has been re moved, and which therefore contains a proportion of caustic alkali solution most favorable to the formation of cellulose xanthate readily soluble in water, the cellulose xanthate which in the present'process forms in and/or on the fibre is, with regard to its properties, different from the cellulose xanthate produced in the processes known hitherto. The latter or at least its greater part is soluble in Water and has normal Viscosity, the former consists, at least partly, of cellulose xanthate insoluble in water, and its component soluble in water, if any, is highly viscous and thus incapable, or only little capable, of penetrating and agglutinating the cellulose fibres, which circumstance is of importancewith regard to the, softness and feel of the final product.

(3) In the processes known hitherto, the whole amount of the cellulose xanthate formed is decomposed in and/or on the cotton fibre, since the cotton treated is brought in contact with the agent decomposing viscose in presence/of the whole amount of the caustic alkali solution which accompanies the cotton throughout the whole process. In contradistinction to this, in the present process, before coming in contact with the agent coagulating viscose and/or before washing, the cotton is removed from the mixture of caustic alkali solution and carbon bisulphide, so that at least the greater part of the soluble xanthate leaves the cotton and remains dissolved in the caustic alkali solution.

Apart from the important fact that the a removal of at least a part of the soluble cel lulose xanthate has a favorable effect on the feel of the finished goods, it has a beneficial infiuence on the-lustre, because, together with the dissolved xanthate, also the outer layer of the cotton is removed. This outer layer has, adhering to it, certain roughnesses which roughnesses considerably affect the lustre. Being exceedingly fine, these roughnesses withstand singeing ii t 'disappear from the cotton fabric or yarn when it is treated according to the present process. Therefore some prominent experts who were able to confirm my observations, call the present process chemical singeing.

According to my present knowledge, it seems therefore, that the silk-like lustre obtainable by the present process is only partly due to the cellulose regenerated from the cellulose xanthate, but more es ecially to the fact that the degree of the swe ling of the cotton fibre, its plasticity and thickening of the cell wall are exceedingly high if the initial swelling in. the caustic alkali solution takes place in presence of carbon 'bisul hide and to the circumstance that at least t e greater part of the soluble cellulose xanthate, on being removed from the treatcdmaterial, carriesaway constituents of the cotton that impair the silk-like lustre produced by the chemical treatment.

According to my invention very valuable properties are imparted to cotton in hank or fabric form when, without previously converting it into alkali-cellulose, it is treated simultaneously with alkali solution and carbon bisulphide, undiluted or diluted with suitable diluents (for example, benzene, chloroform, petrol, petroleum ether, ligroin, carbon tetrachloride or the like). This may be done either by impregnating the cotton or the material consisting of or containing cotton with diluted or undlluted carbon bisulphide and then similarly treating with alkali solution or by subjecting the cotton material to the action of alkali solution to which carbon bisulphide is added before or after the introduction of the cotton- According to the particular nature of the cotton material and the duration of the action of the carbon bisulphide in presence of alkali solution, there are obtained according to the present process either highly-translucent effects with a very silky lustre, or a more or less stifi'ening finishing or both.

The cotton may be treated according to the invention in the form of fabric, of yarns, in hanks or in the form of cops or warps.

The cotton'or the material consisting of or containing cotton, may be treated by the'present process raw or after preliminary treatment (for example boiled, wetted or not wetted, unbleached or bleached with oxidizing or reducing bleaching agents, mercerized or not mercerized).

It may also be treated previously with a hydrolyzing'or gelatinizing agent, for example a strong mineral acid, such as sulphuric acid of 49-60 Baum specific gravity or phosphoric acid of -57 Baum, or higher specific gravity, or hydrochloric acid of 24 Baum specific "ravity, or nitric acid of 43-469 Baum or igher Specific gravity, or hot solution of zinc chloride of Baum specific gravit or an ammonical solution of cu ric oxide 0 considerable concentration.

y reserving certain portions in accordance with known methods (for example by.

the application of substances adopted for this purpose, such as albumin, gum,- acids and the like) pattern .eflectsmay be obtained by the present process.

Mixed goods, that is to say goodscomposed of vegetable and animalfibres, may also be subjected to the present rocess.

By suitable selection 0 the operating conditions there may be' obtained in accordance \with the present process, silky effects surf passing'those obtained by the usual mercerizing methods.

To obtain the silky lustre, stretching of the goodsfis essential. It is immaterial whether the tension is applied before or after the treatment with alkali solution in presence of carbon bisulphide.

' The following examples illustrate the invention:--

1. Bleached or unbleached mercerized or unmercerized cotton fabric is treated under tension with carbon bisulphide undiluted or diluted with benzene (for example 1-5 parts of benzene to 1 part of carbon bisulphide) for some seconds up to a quarter of an hour. Then, where desired aftersqueezing out the excess carbon bisulphide, the fabric is treated with caustic soda solution of 14-20 per cent strength for some minutes up to several hours.

2. Cotton fabric under tension is introduced intoa mixture of caustic soda solution of 10-18 per cent strength with 0.2-3.0 per cent of carbon bisulphide and treated with this mixture for some minutes up to several hours.

3. The mode of operation is as in the foregoing examples, except that before being subjected to the present process the fabric is previously treated with a strong sulphuric acid. If a sulphuric acid of 49-50 Baum specific gravity is used for this purpose, the treatment therewith, at room temperature, may be continued for a few seconds up to some minutes or even longer. If "a stronger splphuric acid is used, for example one of 52-54" Baum specific gravity, the treatment is to occupy only a few seconds, if the sulphuric acid is of room temperature. If the sulphuric acid is cooled to 0 C. or lower, the treatment may be longer.

The treatment with sulphuric acid may be preceded by a mercerizing of the fabric, forin the usual way. It may also be dried or steamed before washing.

All the secondary operations usual in mercerizing or proposed therefor may be applied to the present process for example lustering, printing etc. Y

The finished fabrics may, if desired, be calendered, schreinered, beetled or the like.

The term cotton-in the following claims comprises cotton in the form of pure cotton or mixed fabrics, of yarns, for example, in hanks or cops or warps, either in the pretreated condition, for example, as herein described or the condition in which such pretreatment has not been applied.

I claim:

1. Process of improving cotton, which process comprises treating cotton with caustic alkali and carbon bisulphide in such a manner that the initial swelling oi the cotton fibre by the caustic alkali solution takes place in presence of carbon bisulphide.

2. Process of treating cotton for improving the same, which process comprises subjecting the cotton to treatment with carbon bisulphide and caustic alkali solution, the former bein applied to the cotton at least as soon as the latter.

3. Process of improving otton by treating with caustic alkali and carbon bisulphide, which process comprises treating cotton first with carbon bisulphide and then with caustic alkali solution.

,4. Process of improving cotton by treating with caustic alkali and carbonrbisulphide, which process comprises reacting u on cotton with a mixture of caustic alkali so ution and carbon bisulphide.

5. Process of improving cotton by treating of the cotton into alkali cellulose preparatory for said reaction.

11. Process for improving cotton by treating with caustic alkali and carbon bisulphide, which process comprises treating cotton first with carbon bisulphide and then with caustic alkali solution without previous conversion of the cotton into alkali cellulose preparatory for said treatment.

In testimon whereof I aflix my signature.

)R. LEON LILIENFELD.

with caustic alkali and carbon bisulphide,

which process comprises reacting upon cotton with a mixture of caustic alkali solution and carbon bisulphide, such mixture being formed in the cotton by first impregnating the cotton with carbon bisulphide and then treating the same with a caustic alkali solution.

6. The process as defined in claim 1, wherein the material is stretched during at least part of the treatment.

7. The process as defined in claim 2, wherein the material is stretched during at least part of the treatment. I i

8. The process as defined in claim 3, wherein the material is stretched during at least part of the treatment.

9. The process as defined in claim 4, wherein the materialis stretched during at least part of the treatment.

10. Process for improving cotton by tre atin g with alkali and carbon bisulphide, which proccss comprises reacting upon cotton simultaneously with carbon bisulphide and caustic alkali solution without previous conversion 

